1. Field of the Invention
This invention relates to a video signal switching arrangement for use in a conference to select a video signal from the video signals sent from a plurality of personal computers and projecting the video image of the selected signal; and a conference video display system using same.
2. Description of the Related Art
With the prevalence of personal computers and projectors, conference style has changed from one in which all presenters share a single personal computer and a projector, to one in which a plurality of personal computers and a projector are used. More specifically, conference attendees use their respective personal computers and project video images from the computers selectively.
FIG. 1 shows a conventional video signal switching unit 50 having a plurality of video input connectors 51 for receiving a plurality of video signals, a plurality of switches 52 for selecting one of the video signals inputted, a video output connector 53 for outputting the video signal selected via one of the switches 52, and a power switch 54 for turning the power of the switching unit on/off. With the video signal switching unit 50 of this structure, a conference video display system is established, as shown in FIG. 2, by connecting a plurality of personal computers 55 to the video input connectors 51 of the video signal switching unit 50 via video signal cables 56, and connecting the video output connector 53 of the video signal switching unit 50 to a projector 57 via a video signal cable 58.
In this conference video signal switching system, a person near the video signal switching unit 50 activates one of the switches 52 to selectively project a video image provided by the personal computer 55 desired with the projector 57.
Alternately, a remote controller may be used to perform the switching of the video signal switching unit 50. A related art to the video signal switching unit 50 is disclosed in Japanese Utility Patent No. 3050205.
In the above conventional video signal switching unit 50, however, a person present at the conference who can select video images is limited to the one near the switching unit 50 or a presenter, for example. When the personal computers 55 and the video signal switching unit 50 are randomly connected via the video signal cables 56, it is necessary to examine the correlation in connection between the personal computers 55 and the switches 52 of the video signal switching unit 50, preventing smooth and appropriate video image selection. In particular, when the video signal cables 56 are located within tables or under the floor, it becomes difficult to examine the correlation in connection between the personal computers 55 and the switches 52 of the video signal switching unit 50.
This invention is made to solve the above problem and has an object of providing a video signal switching arrangement which enables attendees at the conference to switch to the video images of their respective personal computers by themselves at will, and provides facilitated and appropriate video image selection without requiring correspondence between the personal computers and the switches in connection, and a conference video display system using the same.
According to a first aspect of the invention, there is provided a video signal switching arrangement having a switching unit for receiving a plurality of video signals and selectively outputting one of the received video signals and a plurality of connection cables for connecting the switching unit to a plurality of personal computers each having a switch, a first cable extending from the switch and being connected at one end thereof to a video signal output of one of the personal computers, and a second cable extending from the switch and being connected to the switching unit at one end thereof, wherein the switch outputs a signal to the switching unit via the second cable to make the switching unit select a video signal sent from the personal computer connected to the switch as the output video signal thereof.
According to a second aspect of the invention, the switch receives a signal for indicating the selection of the personal computer connected thereto when selected, via the second cable; and the switch has an indicator for indicating the selection of the personal computer in response to the received signal.
According to a third aspect of the invention, the second cable has at least one core wire for transmitting a video signal and at least one core wire for transmitting a selection signal.
According to a fourth aspect of the invention, there is provided a connection cable for transmitting a video signal from one end to another end thereof and transmitting an additional signal, comprising first cable for receiving the video signal at one end thereof, a second cable for outputting the video signal and the additional signal from one end thereof, and an additional signal generator including a switch having two statuses for outputting a status signal and an indicator operated based on a signal responding to the status signal, wherein the second cable includes at least one core wire for outputting the status signal and at least one core wire for receiving the signal in response to the status signal.
According to a fifth aspect of the invention, there is provided a conference video display system for selecting an output video signal from video signals sent from a plurality of personal computers, and outputting the output video signal selected to a display device, having a switching unit for receiving a plurality of video signals and selectively outputting one of the received video signals and a plurality of connection cables for connecting the switching unit to the personal computers and outputting video signals from the personal computers to the switching unit each having a switch located near to the personal computer connected thereto to make the switching unit select the video signal sent from the personal computer connected thereto as an output video signal therefrom.